code: def setUpClass(cls):
      cls.backend = "openslide"
  
file_path: MONAI/tests/test_masked_patch_wsi_dataset.py
imports: from __future__ import annotations
  import os
  import unittest
  from unittest import skipUnless
  from numpy.testing import assert_array_equal
  from parameterized import parameterized
  from monai.data import Dataset, MaskedPatchWSIDataset
  from monai.transforms import Lambdad
  from monai.utils import ProbMapKeys, WSIPatchKeys, optional_import, set_determinism
  from tests.utils import download_url_or_skip_test, testing_data_config
label_desc: Use image node_id 1 for calling the TestSlidingPatchWSIDatasetOpenSlide obj's underlying member method code with example usage: obj.setUpClass(cls) without return types